Actuator assembly for hydraulic drive apparatus

ABSTRACT

A hydraulic drive apparatus having an actuator assembly mounted on a control device is disclosed. The hydraulic drive apparatus comprises an input, a hydraulic pump, a control device, and an actuator assembly. The hydraulic drive apparatus is mounted on a vehicle that comprises an operating system. A prime mover drives the input, which subsequently drives one or more axle shafts. The transmission is capable of operation in forward and reverse directions. The control device determines the direction of operation and speed of the transmission. The actuator assembly is mounted to a component of the control device. The actuator assembly determines the state of operation of the output device with respect to the forward or reverse operation of the transmission.

BACKGROUND OF THE INVENTION

This invention relates generally to an actuator assembly that may enableor disable a powered device of a vehicle such as a tractor. Theinvention herein is disclosed in connection with a tractor using anintegrated hydrostatic transaxle. It will be understood that thisinvention can be used with any drive apparatus where a control device isused to adjust an internal swash plate to modify output of a hydraulicpump.

Integrated hydrostatic transaxles (“IHTs”) and switches are well knownin the art and are more fully described in, among others, U.S. Pat. Nos.5,314,387 and 6,951,093, and in U.S. Pat. Nos. 7,032,377 and 7,131,267,the terms of which are incorporated herein by reference. It is alsoknown to use external control devices on IHTs. The external controldevice of this invention is similar to the control device depicted inU.S. Pat. No. 6,880,333, which is incorporated herein in its entirety byreference.

SUMMARY OF THE INVENTION

The invention disclosed herein comprises an actuator assembly that maybe used to enable or disable a powered device depending on the directionan associated control device is moved.

A better understanding of the present invention will be obtained fromthe following detailed descriptions and accompanying drawings, which setforth illustrative embodiments that are indicative of the various waysin which the principles of the invention may be employed. The featuresdisclosed herein can be combined to create a unique design; it isunderstood, however, that such features are unique in their own rightand can be used independently with other transmission, transaxle orvehicle designs. Other benefits and objects of this invention aredisclosed herein and will be obvious to readers of ordinary skill in theart.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a vehicle including a transaxle incorporatingan embodiment of the present invention.

FIG. 2 is a perspective view of the transaxle shown in FIG. 1.

FIG. 3 is a perspective view of certain internal components of thetransaxle shown in FIG. 2.

FIG. 4 is a perspective view of certain components of the controls,including part of the transaxle housing, for the transaxle shown in FIG.2.

FIG. 5 is a perspective view of the components shown in FIG. 4, with thecontrols in the neutral position and with the bearing retainer removed.

FIG. 6 is a side view of the control arm, return arm and actuatorassembly of the transaxle shown in FIG. 2 with the control arm at theneutral position and with the bearing retainer removed.

FIG. 7 is a side view similar to that of FIG. 6, with the control arm ata reverse position.

FIG. 8 is a side view similar to that of FIG. 6, with the control arm ata maximum reverse position.

FIG. 9 is a side view similar to that of FIG. 6, with the control arm ata maximum forward position.

FIG. 10 is a side view of an embodiment of the actuator assembly, withthe actuator arm in the first position.

FIG. 11 is a view similar to FIG. 10, with the actuator arm in thesecond position.

FIG. 12 is a view similar to FIG. 10 with the switch removed from theactuator assembly and the actuator arm in the first position.

FIG. 13 is a view similar to FIG. 11 with the switch removed from theactuator assembly and the actuator arm in the second position.

FIG. 14 is a perspective view of the base and spring assembly of anembodiment of the actuator assembly.

FIG. 15 is a partially exploded view of an embodiment of the control armand actuator assembly.

FIG. 16 is an exploded view of an embodiment of the actuator assembly.

FIG. 17 is a perspective view of a selected portion of the transaxleused in an alternative embodiment.

FIG. 18 is a side view of the control arm, return arm and actuatorassembly of the transaxle shown in FIG. 17 at the neutral position.

FIG. 19 is a side view of the control arm, return arm and actuatorassembly of the transaxle shown in FIG. 17 with the control arm at themaximum reverse position.

FIG. 20 is a side view of the control arm, return arm and actuatorassembly of the transaxle shown in FIG. 17 at a forward position.

FIG. 21 is a view of the actuator assembly shown in FIGS. 18-20 in thesecond position.

DETAILED DESCRIPTION OF THE DRAWINGS

As noted above, this invention is described herein with respect to avehicle including an integrated hydrostatic transaxle, but it will beunderstood that this invention is not limited to such an application. Itis contemplated that the present invention can also be used with otherdrive apparatus designs where a control arm is used to modify the outputof a hydraulic pump. Identical structure in different embodiments isgiven identical numerals throughout; where appropriate, differentprefixes are used to differentiate between structures that are similarbut not identical.

The embodiment depicted in FIG. 1 shows a typical vehicle 36 having aprime mover or engine 29 mounted on a vehicle frame 31, rear drivewheels 21 and front steering wheels 23; one of rear drive wheels 21 hasbeen removed from this figure for clarity. Mower deck 20 may also beprovided on vehicle 36. Each of these elements and accompanyinginterconnections are well known in the art and will not be described indetail.

In the depicted embodiment, exemplary hydrostatic transaxle 10 ismounted towards the rear of vehicle 36 to power both drive wheels 21.Hydrostatic transaxle 10 is shown in more detail in FIGS. 2 and 3.Hydrostatic transaxle 10, as depicted herein, is similar to that shownin U.S. Pat. No. 6,253,637, the terms of which are incorporated hereinby reference in its entirety. However, it will be appreciated that theuse of other hydrostatic transaxles is within the scope of the presentinvention. Hydrostatic transaxles, such as hydrostatic transaxle 10, arewell known in the art and will only generally be described here. Thedepicted embodiment of hydrostatic transaxle 10 comprises hydraulic andgear elements located inside transmission housing 11. Transmissionhousing 11 has been removed in FIG. 3 so that the internal interactionof pump assembly 14, swash plate 18, trunnion arm 16 and hydraulic motor24 can be seen. Generally, pump assembly 14 is mounted on center section22 and driven by input shaft 12. Pump assembly 14 is hydraulicallyconnected to hydraulic motor 24, also mounted on center section 22,through hydraulic porting (not shown) formed in center section 22.Hydraulic motor 24 in turn drives motor shaft 26 which transmits powerthrough gear 27 to gear train 28, driving output axles 30. Swash plate18 is proximate to pump assembly 14 such that the angular movement ofswash plate 18 regulates the hydraulic output of pump assembly 14, whichin turn controls the direction and speed of hydraulic motor 24.

As depicted in, for example, FIGS. 1-5, swash plate 18 is rotated bytrunnion arm 16. To aid a user in rotating swash plate 18 with trunnionarm 16, control arm 40 of control device 39 may be mounted on trunnionarm 16. In the depicted embodiment, control device 39 comprises controlarm 40 and return-to-neutral mechanism 43, with return-to-neutralmechanism 43 comprising return arm 42, retainer assembly 33, bias spring38, bearing 55 and bearing retainer 56. Control devices are generallywell known in the art, and it will be obvious that any number ofconfigurations of control device 39 fall within the scope of the presentinvention.

In the depicted embodiment, control arm 40 is connected to a regulatingdevice, such as pedal 34, provided on vehicle 36. Movement of pedal 34is translated to control arm 40 through linkage (not shown), which inturn causes rotation of trunnion arm 16 and angular movement of swashplate 18.

As is generally known, swash plate 18 has a neutral position, and may berotated to a plurality of forward positions, as well as a plurality ofreverse positions, wherein any of the plurality of forward positions mayequate to forward travel of vehicle 36, while any of the plurality ofreverse positions may equate to the reverse travel of vehicle 36. In theneutral position, swash plate 18 is positioned for minimal fluiddisplacement of pump assembly 14. When swash plate 18 is rotated to anyof the plurality of forward positions, pump assembly 14 displaceshydraulic fluid so as to cause rotation of hydraulic motor 24, and thusmovement of gear train 28 and axles 30, in a forward direction, relativeto vehicle 36. Similarly, when swash plate 18 is rotated to any of theplurality of reverse positions, vehicle 36 will be propelled in areverse direction. As control arm 40 is coupled with swash plate 18through trunnion arm 16, control arm 40 also has a neutral position, aplurality of forward positions and a plurality of reverse positions,each of which corresponds to the positions of swash plate 18,respectively. For the purposes of this discussion, a forward position ofa control arm or swash plate corresponds to forward travel of vehicle36, but does not necessarily specify the direction of movement of acontrol arm or swash plate with respect to vehicle 36.

In the embodiment depicted, for example, in FIGS. 1, 2 and 4,return-to-neutral mechanism 43 may be provided to bias control arm 40into the neutral position. As shown, return-to-neutral mechanism 43 maycomprise bias spring 38 and return arm 42, which cooperates with controlarm 40 to urge control arm 40 toward the neutral position, absent inputfrom an operator. In the embodiment depicted, for example, in FIG. 4,return arm 42 engages control arm 40 through bearing 55.

Control arm 40 includes formed edge areas 40 a, 40 b and 40 c, whichcorrespond to the plurality of forward and reverse positions and theneutral position of control arm 40, respectively, as discussed in detailbelow. Bearing retainer 56 is positioned adjacent to bearing 55 and aidsin aligning bearing 55 with formed edge areas 40 a-40 c. In theembodiment depicted in FIGS. 4-6, formed edge areas 40 a-40 c are shapedsuch that the force from bias spring 38 maintains bearing 55 on edgearea 40 c of control arm 40, absent operator input. As an operatorrotates control arm 40 through linkage (not shown) connected to pedal34, to any of the plurality of forward positions, bearing 55 will movealong formed edge 40 a, as depicted, for example, in FIG. 9. As anoperator rotates control arm 40 to any of the plurality of reversepositions, bearing 55 will move along formed edge area 40 b, asdepicted, for example, in FIG. 8. To achieve forward movement of vehicle36, control arm 40 is rotated clockwise about opening 41 in FIG. 9.Control arm 40 and return arm 42 may be mounted to transaxle 10 as seenin FIG. 2. Control arm 40 includes an opening 41 through which trunnionarm 16 may be disposed. Return arm 42 is mounted to transaxle 10 by aretainer assembly 33, which permits adjustment of the position of returnarm 42 to establish the neutral position.

Actuator assembly 44 is shown most clearly in FIGS. 10-16 and comprisesactuator arm 78 rotatably mounted on pivot 80 of actuator base 74, androtatable between a first and a second position. Actuator assembly 44 issecured to control arm 40 with fasteners 46. Fasteners 46 extend throughopenings 60 in actuator base 74 into holes 62 formed in control arm 40.Switch 66 is located on actuator base 74 by protrusions 76, extendingthrough openings 68. Switch 66 has a second state, which corresponds tothe normal state of switch 66, and a first state. Switch 66 may benormally closed or normally open. As described in detail below, actuatorarm 78 forces switch 66 to the first state when actuator arm 78 is inthe first position. Conversely, actuator arm 78 allows switch 66 tomaintain its second or normal state when actuator arm 78 is in thesecond position. With actuator arm 78 positioned on actuator base 74 asshown in FIG. 11, protrusions 76 locate switch 66 so that switch 66 isin proximity to recess 88 formed in actuator arm 78. Actuator biasspring 82 is positioned in recess 84, formed in actuator base 74. Theinteraction of spring 82 with ridges 86 aids in the retention of spring82 in recess 84 during assembly.

In the depicted embodiment, as shown in FIG. 15, actuator base 74 isformed such that, when actuator assembly 44 is attached to control arm40, a small gap is formed between actuator arm 78 and control arm 40. Inthis manner, actuator arm 78 may rotate with respect to both actuatorbase 74 and control arm 40. The attachment of actuator base 74 tocontrol arm 40 further retains switch 66 on actuator base 74 which inturn further retains spring 82 in recess 84.

As previously noted, actuator assembly 44 is mounted to control arm 40by fasteners 46 extending through openings 60. Openings 60 may beslotted to allow adjustment of actuator assembly 44 such that, whenactuator arm 78 is in the first position shown in, for example, FIGS. 4,5 and 6, edge 78 a of actuator arm 78 is in alignment with formed edgearea 40 a of control arm 40. Furthermore, the contour of actuator arm 78may be approximately the same as the contour of formed edge area 40 a.In the depicted embodiment, edge 78 a and formed edge area 40 a arecurvilinear. It will be appreciated, however, that the scope of thepresent invention includes an embodiment where edge 78 a and formed edgearea 40 a are linear. Thus, in the depicted embodiment, as control arm40 is rotated to the neutral position or any of the plurality of forwardpositions, bearing 55 will remain in contact with both formed edge area40 a of control arm 40, as well as edge 78 a of actuator arm 78,maintaining both actuator arm 78 in the first position and switch 66 inthe first state.

Proper positioning of actuator assembly 44 on control arm 40 isimportant; if actuator assembly 44 is positioned too far below the edgeof control arm portion 40 a, then actuator arm 78 may have insufficientmovement to actuate switch 66. If actuator assembly 44 is positioned toonear the edge of control arm portion 40 a then the contact betweenbearing 55 and actuator arm 78 may cause damage to actuator arm 78 andpossibly to other elements of actuator assembly 44. Slotted openings 60permit adjusting the position of actuator assembly 44 prior to securingfasteners 46.

As seen more clearly in FIGS. 16 and 10-11, stop 72 may be formed onpivot 80 and cooperate with recess 73, formed adjacent to opening 79 inactuator arm 78, to restrict the movement of actuator arm 78. Asactuator arm 78 rotates to the first position, as seen, for example, inFIGS. 4, 6, 9, and 10, stop 72 may contact wall 73 a of recess 73, toprovide one limit of movement of actuator arm 78. As actuator arm 78rotates to the second position, as seen, for example, in FIGS. 7, 8 and11, stop 72 will contact wall 73 b of recess 73 to provide another limitof movement of actuator arm 78.

In the depicted embodiment, the above-defined components operate asfollows. Return-to-neutral mechanism 43 initially biases control arm 40to the neutral position, where bearing 55 is in contact with formed edgearea 40 c of control arm 40 and edge 78 a of actuator arm 78. Byengaging actuator arm 78, bearing 55 urges actuator arm 78 into thefirst position, thus causing switch 66 to enter its first state. It willbe appreciated by those in the art that the scope of the presentinvention includes bearing 55 being disengaged from actuator arm 78 whencontrol arm 40 is in the neutral position.

As an operator moves a vehicle control such as, for example, pedal 34,to any of the forward positions, the linkage from the vehicle controlcauses a proportional movement of control arm 40. Movement of controlarm 40 to any of the forward positions causes bearing 55 to travel alongformed edge area 40 a of control arm 40, as well as along edge 78 a ofactuator arm 78, continuing to maintain actuator arm 78 in the firstposition. If bearing 55 is disengaged from actuator arm 78 when controlarm 40 is in the neutral position, movement of control arm 40 to any ofthe forward positions will cause bearing 55 to engage actuator arm 78.When actuator arm 78 is rotated to the first position, it depressesplunger 92, as seen, for example, in FIG. 10, causing switch 66 to enterthe first state.

As an operator moves a vehicle control, such as pedal 34, to any of thereverse positions, the vehicle control linkage causes a proportionalmovement of control arm 40 and bearing 55 travels along formed edge area40 b of control arm 40. This movement is depicted most clearly in FIGS.7 and 8. As control arm 40 is moved to any of the reverse positions,bearing 55 disengages from edge 78 a of actuator arm 78 allowing spring82 and any bias spring (not shown) internal to switch 66, to forceactuator arm 78 to the second position. As actuator arm 78 moves to thesecond position, plunger 92 is no longer depressed, and switch 66maintains the second state. The exact angle at which bearing 55disengages from edge 78 a will depend on a number of variables. In theexample shown in this embodiment, the angle of control arm 40 isapproximately 1.5° from neutral when bearing 55 disengages from edge 78a.

The depicted embodiment allows for a number of variations depending onthe needs of the user. In one embodiment, the second state of switch 66may correspond to a closed state, which would provide a connection to anoperating system. By way of example, and in no way limiting, if leads 64are connected to an engine circuit (not shown) on one side and ground onthe other side, allowing switch 66 to enter its second state will causeengine 29 to be grounded, thus stopping operation of engine 29.

In another embodiment, switch 66 may be used with a power take off (notshown) to control the function of mower deck 20. With this type ofconfiguration, operation in neutral or in the forward direction wouldcause switch 66 to be closed, permitting operation of the electric powertake off, which would thus allow mower deck 20 to operate. Conversely,operation in the reverse direction would cause switch 66 to be open,removing electrical power from the power take off, thus causing mowerdeck 20 to cease operation.

In yet another embodiment, the second state of switch 66 may correspondto a closed state, which would provide power to an operating system. Asan example, without limitation, switch 66 may be used in conjunctionwith an electric alarm (not shown). In this type of configuration,movement of control arm 40 to the neutral position or any of the forwardpositions would cause switch 66 to be in the open state, removing powerfrom the alarm. Conversely, movement of control arm 40 to any of thereverse directions would cause switch 66 to be in its normal or closedcondition, supplying electrical power to the alarm, causing the alarm tooperate.

An alternative embodiment of the present invention is depicted in FIGS.17-21. In this configuration, transaxle 110 is similar to transaxle 10described above. For simplicity, some elements of transaxle 110 havebeen removed in FIG. 17.

The embodiment depicted in FIG. 17 comprises transaxle housing 111,control arm 140, return arm 142, retainer assembly 133, bias spring 138,fastener 117 that attaches control arm 140 to a trunnion (not shown),and bearing 155 with bearing retainer 156. Return arm 142 is mounted totransaxle 110 by a retainer assembly 133, which permits adjustment ofreturn arm 142 to establish a neutral position for control arm 140.

As described above, control arm 140 has a neutral position, a pluralityof forward positions and a plurality of reverse positions. In thedepicted embodiment, control arm 140 is biased in the neutral positionby return-to-neutral mechanism 143, which includes bias spring 138,return arm 142 and retainer assembly 133. Bearing 155 is mounted oncontrol arm 140 and interacts with formed edge areas 142 a-c of returnarm 142. When in the neutral position, bearing 155 is biased to the areaof formed edge area 142 c in the absence of operator input. As anoperator rotates control arm 140 to any of the forward positions,bearing 155 will move along formed edge area 142 a. As an operatorrotates control arm 140 to any of the reverse directions, bearing 155will move along formed edge area 142 b. The movement of bearing 155along formed edge areas 142 a-c is shown in, for example, FIGS. 20, 19and 18, respectively.

As depicted in FIGS. 17-21, actuator assembly 144 comprises actuator arm178, actuator base 174 and switch 166. Actuator assembly 144 may besecured to return arm 142 with fasteners 146, which extend throughopenings 160 in actuator base 174, into holes (not shown) formed inreturn arm 142. Actuator arm 178 is rotatably located on actuator base174 by pivot 180, as seen in FIG. 21, and may be rotated between a firstand a second position. Protrusions 176 extend through openings 168 inswitch 166 and act to position switch 166 within recess 188, formed inactuator base 174. Spring 182 is positioned in recess 184 which isformed in actuator arm 178. Spring 182 interacts with ridges 186 to aidthe retention of spring 182 in recess 184 during assembly.

As previously described, openings 160 may be slotted to allow adjustmentof the actuator assembly 144 position, and particularly of actuator arm178, aiding in the alignment with formed edge area 142 a. In theembodiment depicted, for example, in FIG. 18, the contour of actuatorarm 178 may be approximately the same as the contour of formed edge area142 a. In this manner, bearing 155 will remain in contact with actuatorarm 178 when control arm 140 is in the neutral position or any of theforward positions. It will be understood that the scope of the presentinvention includes an embodiment wherein bearing 155 will remain incontact with actuator arm 178 when control arm 140 is in any of theforward positions, and will disengage from actuator arm 178 when controlarm 140 is in the neutral position, or is rotated to any of the reversepositions.

The embodiment depicted, for example, in FIGS. 17-21, also includesfeatures that limit the range of movement of actuator arm 178. Asactuator arm 178 is rotated toward the second position, portion 174 b ofactuator base 174 acts as a stop against actuator arm 178 by contactingactuator arm 178 and limiting the movement of actuator arm away fromplunger 192 to the position shown in FIGS. 19 and 21. As actuator arm178 is rotated toward the first position, actuator base portion 174 alimits the movement of actuator arm 178 to the position shown in FIGS.18 and 20. Portion 174 a is enabled as a stop due to plunger boot 158compressing into switch 166 when actuator arm 178 depresses plunger 192.Further, spring 182 compresses entirely into recess 184 when actuatorarm 178 rotates toward switch 166. The spring 182 compression intorecess 184 allows actuator assembly 144 to be more compact.

It is to be understood that the above description of the inventionshould not be used to limit the invention, as other embodiments and usesof the various features of this invention will be obvious to one skilledin the art. This invention should be read as limited by the scope of itsclaims only.

1. A hydraulic drive apparatus mounted on a vehicle comprising anoperating system having a first and a second operating state, thehydraulic drive apparatus comprising: a housing; a hydraulic pumplocated within the housing; a control device, at least a portion ofwhich is coupled to the hydraulic pump to control the hydraulic pumpfluid flow, the control device movable among a neutral position, aplurality of reverse positions and a plurality of forward positions, thecontrol device comprising: a first control device component; and asecond control device component; and an actuator assembly mounted to thefirst control device component and selectively engaged to the secondcontrol device component, the actuator assembly connected to theoperating system, wherein the actuator assembly causes the operatingsystem to be in the first operating state when the control device is inthe neutral position or is rotated to any of the forward positions andthe actuator assembly causes the operating system to be in the secondoperating state when the control device is in any of the reversepositions.
 2. The hydraulic drive apparatus of claim 1, furthercomprising a bearing mounted on the second control device component andengaged to the first control device component, the bearing moveablealong a first, a second and a third edge portion, each edge portionformed on the first control device component, wherein and the secondcontrol device component is rotatable with respect to the first controldevice component.
 3. The hydraulic drive apparatus of claim 2, whereinthe actuator assembly comprises: an actuator base mounted on the firstcontrol device component; a switch having a first and a second state,which correspond to the first and second state of the operating system,respectively, wherein the switch is disposed on the actuator base andconnected to the operating system; and an actuator arm moveably engagedto the actuator base and alternately engaged to the bearing, theactuator arm moveable between a second position, which allows the switchto maintain the second state, and a first position, which causes theswitch to enter the first state, wherein engagement with the bearingforces the actuator arm into the first position.
 4. The hydraulic driveapparatus of claim 3, wherein the bearing is engaged to the first edgeportion of the first control device component and to the actuator armwhen the control device is in the neutral position.
 5. The hydraulicdrive apparatus of claim 3, wherein rotation of the control device toany of the forward positions causes the bearing to move along the secondedge portion of the first control device component and to move along theactuator arm.
 6. The hydraulic drive apparatus of claim 3, whereinrotation of the control device to any of the reverse positions causesthe bearing to move along the third edge portion of the first controldevice component and disengage the actuator arm.
 7. The hydraulic driveapparatus of claim 1, wherein the first control device component is acontrol arm, engaged to the hydraulic pump and rotatable between aplurality of control arm forward positions that correspond to theforward positions of the control device, a control arm neutral positionthat corresponds to the neutral position of the control device and aplurality of control arm reverse positions that correspond to thereverse positions of the control device.
 8. The hydraulic driveapparatus of claim 7, wherein the second control device component is areturn-to-neutral mechanism, comprising a return arm rotatably engagedto the hydraulic drive apparatus and a return-to-neutral spring engagedto the return arm and the hydraulic drive apparatus, wherein thereturn-to-neutral mechanism biases the control arm to the control armneutral position.
 9. The hydraulic drive apparatus of claim 1, whereinthe second control device component is a control arm, engaged to thehydraulic pump and rotatable between a plurality of control arm forwardpositions that correspond to the forward positions of the controldevice, a control arm neutral position that corresponds to the neutralposition of the control device and a plurality of control arm reversepositions that correspond to the reverse positions of the controldevice.
 10. The hydraulic drive apparatus of claim 9, wherein the firstcontrol device component is a return-to-neutral mechanism, comprising areturn arm rotatably engaged to the hydraulic drive apparatus, and areturn-to-neutral spring engaged to the return arm and the hydraulicdrive apparatus, wherein the return-to-neutral mechanism biases thecontrol arm to the control arm neutral position.
 11. A hydraulic driveapparatus comprising: a housing; a variable displacement hydraulic pumpdisposed within the housing; a trunnion arm movable to control thedisplacement of the hydraulic pump; a control arm attached to thetrunnion arm; a return-to-neutral mechanism attached to the housingcomprising a bearing, the bearing engaged to the control arm andpositioned to bias the control arm to a neutral position; and anactuator assembly attached to the control arm generally adjacent to anedge of the control arm, the actuator assembly comprising an actuatorarm and a switch, wherein the actuator arm is selectively engaged to thebearing and movable between a first position, which causes the switch toenter a first state, and a second position, which allows the switch tomaintain a second state; wherein the bearing engages the actuator arm,causing the actuator arm to move to the first position, when the controlarm is moved to the neutral position or any of a plurality of forwardpositions, and wherein the bearing disengages the actuator arm, allowingthe actuator arm to move to the second position, when the control arm ismoved to any of a plurality of reverse positions.
 12. The hydraulicdrive apparatus of claim 11, wherein the actuator arm has a profilegenerally similar to the profile of the edge of the control arm.
 13. Thehydraulic drive apparatus of claim 12, wherein the actuator arm isrotationally mounted on an actuator base, and wherein the actuator baselimits the movement of the actuator arm by contact with the actuatorarm.
 14. The hydraulic drive apparatus of claim 13, wherein movement ofthe actuator arm is limited by a stop formed on the actuator base whichinteracts with walls formed in a pivot opening of the actuator arm. 15.The hydraulic drive apparatus of claim 11, further comprising anactuator arm bias spring fixedly positioned in an actuator base andengaged to the actuator arm, the actuator arm bias spring biasing theactuator arm to the second position.
 16. The hydraulic drive apparatusof claim 15, wherein the switch is fixedly positioned on the actuatorbase and cooperates with the actuator base and actuator arm to retainthe actuator arm bias spring in the actuator base.
 17. The hydraulicdrive apparatus of claim 11, wherein an actuator base is attached to andcooperates with the control arm to retain the actuator arm and theswitch.
 18. The hydraulic drive apparatus of claim 11, furthercomprising an actuator base wherein an actuator arm bias spring isretained on the actuator base by ridges and the actuator arm isrotatably mounted on the actuator base.
 19. The hydraulic driveapparatus of claim 11, wherein the profile of the control arm and theprofile of the actuator arm are curvilinear.
 20. A hydraulic driveapparatus comprising: a housing; a variable displacement hydraulic pumpdisposed within the housing; a trunnion arm movable to control thedisplacement of the hydraulic pump; a control arm mounted on thetrunnion arm and moveable among a neutral position, a plurality ofreverse positions and a plurality of forward positions, the control armcomprising a bearing; a return arm attached to the housing, wherein thereturn arm is engaged to the bearing to bias the control arm to theneutral position; and an actuator assembly attached to the return armgenerally adjacent to an edge of the return arm, the actuator assemblycomprising an actuator arm and a switch, wherein the actuator arm isselectively engaged to the bearing and movable between a first position,which causes the switch to enter a first state, and a second position,which allows the switch to maintain a second state; wherein the bearingengages the actuator arm, causing the actuator arm to move to the firstposition when the control arm is moved to the neutral position or any ofthe plurality of forward positions, and wherein the bearing disengagesthe actuator arm, allowing the actuator arm to move to the secondposition, when the control arm is moved to any of the plurality ofreverse positions.
 21. The hydraulic drive apparatus of claim 20,wherein the actuator arm has a profile generally similar to the profileof the edge of the return arm.
 22. The hydraulic drive apparatus ofclaim 20, wherein the actuator arm is rotatably mounted on an actuatorbase, and wherein the actuator base limits the movement of the actuatorarm by contact with the actuator arm.
 23. The hydraulic drive apparatusof claim 20, wherein an actuator arm bias spring is fixedly positionedin the actuator arm, and the actuator arm cooperates with an actuatorbase to retain the bias spring in the actuator arm.
 24. The hydraulicdrive apparatus of claim 20, wherein the profile of the actuator arm isbiased to a position that is misaligned with the profile of the returnarm by an actuator bias spring when the bearing is disengaged from theactuator arm.
 25. The hydraulic drive apparatus of claim 24, wherein theactuator bias spring is retained on the actuator arm by ridges.
 26. Thehydraulic drive apparatus of claim 20, wherein the profile of the returnarm and the profile of the actuator arm are linear.
 27. A hydraulicdrive apparatus mounted on a vehicle comprising an operating systemhaving a first and a second operating state, the hydraulic driveapparatus comprising: a housing; a hydraulic pump located within thehousing; a control device, at least a portion of which is coupled to thehydraulic pump to control the hydraulic pump fluid flow, the controldevice movable to a neutral position, a plurality of reverse positions,and a plurality of forward positions, the control device comprising: afirst rotatable arm having a profile; a second arm rotatable withrespect to the first rotatable arm and having a bearing mounted thereon;and a switch mounted on the first rotatable arm and connected to theoperating system, wherein the bearing moves along the profile andselectively engages the switch, wherein the switch causes the operatingsystem to be in the first operating state when the bearing is disengagedfrom the switch and the switch causes the operating system to be in thesecond operating state when the bearing moves along the profile toengage the switch.
 28. The hydraulic drive apparatus of claim 27,wherein the first rotatable arm is a control arm and the second arm is areturn arm, and the bearing interacts with the profile of the controlarm to bias the control arm to the neutral position.
 29. The hydraulicdrive apparatus of claim 27, wherein the first rotatable arm is a returnarm and the second arm is a control arm, and the bearing interacts withthe profile of the return arm to bias the control arm to the neutralposition.